Presently, the only two known nucleosidic antibiotic agents having 5-membered heterocyclic rings are showdomycin and pyrazomycin, which have respectively been reported to have structures (1) and (2): ##STR1## Among the presently known synthetic nucleosidic antiviral agents, the more important are 5-iodo-2'-deoxyuridine (5-IDU) 9-.beta. -D-arabinofuranosyl adenine (Ara-A) and 1-.beta. -D-arabinofuranosyl cytosine (Ara-C). Of these agents, only 5-IDU (in 0.1% wt. solution) is commercially available specifically as an antiviral agent, and this compound suffers the disadvantage of low solubility and high toxicity, from whence arises the undesirably great dilution in which it is now employed.
Alsonso et al. in J. Heterocyclic Chem. 7, 1269-72 (1970) report the preparation of 1-(.beta. -D-ribofuranosyl)-4-carboxamido-1,2,3-triazole but make no mention of biological activity. Witkowski and Robins, in "The Chemical Synthesis of the 1,2,4-Triazole Nucleosides Related to Uridine, 2'-Deoxyuridine, Thymidine and Cytidine," J. Org. Chem. 35, 2635-41 (1970) suggest various 1,2,4-triazole nucleoside analogs as candidates for biological testing, but no particular efficacy is noted and our later testing has shown that, of the analogs there reported, only 5-bromo-3-nitro-1-(2,3,5-tri-O-acetyl-.beta. -D-ribofuranosyl)-1,2,4-triazole exhibits even slight antiviral activity and even this activity is believed to be attributable merely to the cytotoxicity of the compound.